WO1997022098A1

WO1997022098A1 - Reflective sheet

Info

Publication number: WO1997022098A1
Application number: PCT/JP1995/002538
Authority: WO
Inventors: Katsura Ochi; Osamu Tanaka; Masaki Yoshizawa
Original assignee: Nippon Carbide Kogyo Kabushiki Kaisha
Priority date: 1994-06-13
Filing date: 1995-12-12
Publication date: 1997-06-19
Also published as: DE69528668D1; US6110574A; EP0809225A4; EP0809225A1; JP3310300B2; EP0809225B1; DE69528668T2

Abstract

A reflective sheet having a smooth surface layer where light is incident, which includes a fluororesin film having a total transmittance of 80 % or greater on the surface layer. Even when this reflective sheet is used in a cold place, the surface thereof is substantially free from icing and the deposition of snow, and it can be easily cleaned if it has scribbles in paint and ink.

Description

Specification

Retroreflective sheet

Technical field

INDUSTRIAL APPLICABILITY The present invention is useful for signs such as road signs and construction signs; number plates of vehicles such as automobiles and motorbikes; safety materials such as clothes and lifesaving equipment; sports goods such as snow poles; and marking materials such as signboards. There is little icing or snow accretion on the surface of the retroreflective sheeting even when used in cold climates, and even when the surface of the retroreflective sheeting is contaminated with paint, ink, etc. The present invention relates to a retroreflective sheet excellent in decontamination property that can easily remove contamination only by wiping with water or rinsing without using any other means.

Background art

Conventionally, a retroreflective sheet that retroreflects light toward a light source is well known, and by utilizing the retroreflective property, the sheet is widely used in various fields as described above.

However, these conventional retroreflective sheets have various problems, particularly when used in cold climates.For example, in the winter, when the temperature drops below zero, they adhere to the surface of the retroreflective sheet. Water droplets freeze and the retroreflective performance is reduced, and when snow falls, snow adheres to the surface of the retroreflective sheeting, and on significant stands, the display function as a sign is completely lost. In cold regions, problems such as reduced visibility due to ice, snow, etc., and reduced retroreflective performance often occur.

Several attempts to prevent freezing and snow accretion in such cold regions have been proposed in the past, for example, in US Pat. No. 5,087,508. The detailed description discloses a method of arranging a heat storage material on a sign and preventing heat from freezing and snow accretion. However, this method has problems such as the complexity of attaching the heat storage material to the sign and the cost of attaching the sign, and it is very difficult for widespread practical use. Drawbacks

In addition, recently, the surface of signs, such as road signs and construction signs, has been contaminated by mischief such as paint and ink, causing problems such as deterioration of the sign display function, which has become a problem. Several attempts have been made to remove the contaminants from such contaminated signs and restore the lost functions. For example, an acrylic frame has been mounted on the surface of a retroreflective sheet. A method of applying a solution such as a bridge-type resin and drying to provide a surface layer with strong solvent resistance, and in the case of contamination, wiping off the contamination with an organic solvent to remove it, etc. are being implemented. However, this method has a disadvantage in that a solvent for dissolving the contaminants is absolutely required for decontamination, which has a negative effect on workers and a negative effect on the environment. Further, a so-called encapsulated lens-type retroreflective sheet in which at least a part of the retroreflective sheet is made of a fluororesin film is also known. Japanese Patent Application Publication No. 6701 discloses an ultra-weather resistant structure in which high refractive glass beads and a focusing layer film are sequentially laminated on a surface layer made of a fluororesin film, and a metal layer is formed on the focusing layer film. Sexual retroreflective sheets are disclosed.

According to the publication, the above-mentioned ultra-weather-resistant retroreflective sheet is formed by applying a paint containing a fluorine-based resin solution as a main component on an appropriate support film and drying it to form a fluorine-based resin surface layer. On this surface layer, a binder layer film After coating and drying, the glass beads are embedded in the binder layer film, a coating for the focal layer film is applied thereon, dried, and then a metal reflective layer is formed on the focal layer film. It is also disclosed that an intermediate layer can be provided between the surface layer and the binder layer in the same manner.

However, in the case of resins having a low surface tension, such as fluororesins, many of them have poor solubility in organic solvents, and when preparing an organic solvent solution of such a resin, the selection range of the resin becomes narrower. There are problems such as difficulty in selecting an organic solvent, and the present situation is that satisfactory retroreflective sheets have not always been obtained.

In view of these drawbacks of the prior art, an object of the present invention is to provide a retroreflective sheet with frost resistance and snow resistance by a simple operation, and further to provide a retroreflective sheet such as a sign. Even if the surface of the product is contaminated with paint, ink, etc., it can be easily contaminated only by wiping with water and rinsing without using a wiping solvent that has a negative effect on the human body and the environment. The object is to provide an improved retroreflective sheet that can be removed.

Disclosure of the invention

The present inventors have developed various methods for improving the icing and snow accretion on the surface of a retroreflective sheet, which is a problem in cold regions, and for improving the ease of removing the retroreflective sheet from contamination. As a result of this study, this time, a very simple operation of joining a transparent fluororesin film to the surface of the retroreflective sheet on the light-incident side via an adhesive layer was performed. Significantly improved ice resistance, snow resistance and ease of decontamination. W

Four

I found it.

Thus, according to the present invention, the fluororesin film having a total light transmittance of 80% or more is provided on the surface of the retroreflective sheet having the smooth surface layer on the light incident side by the adhesive layer. A retroreflective sheet laminated through the

5

Hereinafter, the retroreflective sheet of the present invention will be described in more detail. The type of the retroreflective sheet to which the fluororesin film is adhered according to the present invention is not particularly limited as long as it has a smooth surface on the light incident side (ie, has a flatfrontfac e).

For example, it is possible to use a retroreflective sheet such as an encapsulated lens type retroreflective sheet, a capsule lens type retroreflective sheet, a capsule cube corner type retroreflective sheet, and a metallized cube corner type retroreflective sheet. it can. These retroreflective sheets and a method for producing the same are described in, for example, Japanese Patent Publication No. 56-29211 (US Patent No. 4,025,674). In addition, a capsule lens type retroreflective sheet is disclosed in Japanese Patent Application Laid-Open No. 60-194405 (U.S. Pat. No. 4,653,854). A reflective sheet is disclosed in U.S. Pat. No. 3,417,959, and a metallized tube corner type retroreflective sheet is disclosed in Japanese Patent Application Laid-Open No. 49-10669. (U.S. Pat.

2012, 706), etc., and the specific descriptions of these references are used here instead of these references.

The present invention is characterized in that a fluororesin film is adhered on the smooth light incident side surface layer of the retroreflective sheet as described above.

The fluororesin film to be adhered has a total light transmittance of 80% or more. Those having high transparency of preferably 85% or more, more preferably 90% or more are used. In the present specification, the total light transmittance of the fluororesin film is a value measured using a “Haze Meter TC-HIII” (manufactured by Tokyo Denshoku Co., Ltd.).

The thickness of the fluorine-based resin film is not particularly limited, and can be varied over a wide range according to the use of the retroreflective sheet. , Preferably 5 to 80 zm, more preferably 10 to 70 m, even more preferably 20 to 60 m.

Examples of fluororesins that can be used for the production of such films include, for example, fluorofluorinated resins such as tetrafluoroethylene, black trifluoroethylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride, and hexafluoropropylene. Monomers; Homopolymers such as perfluoroalkyl vinyl ethers, perfluoroalkyl (meth) acrylic monomers and other fluorine-containing monomers other than fluororefin-based monomers; It is necessary to use a copolymer of these fluorine-containing monomers or a copolymer of these fluorine-containing monomers with another copolymerizable monomer, or a mixture of these (co) polymers with another resin. Can be.

Examples of the above-mentioned copolymerizable monomers include: olefin-based monomers such as ethylene and propylene; methyl vinyl ether, ethylvinyl ether, n-butynolevinolene ether, and cyclohexylvininole ether. （, (Cyclo) alkyl vinyl ether monomers such as cyclopentyl vinyl ether; vinyl acetate, vinyl propionate, vinyl bivalate, “vinyl versatate” (trade name, manufactured by Shell), vinyl benzoate, p-t-butyl Vinyl carboxylate monomers such as vinyl benzoate, cyclohexane carboxy vinyl, and isopropenyl acetate; vinyl halide monomers other than fluorine-containing monomers such as vinyl chloride and vinylidene chloride; methyl (Meta) acrylate, ethyl (meta) acrylate, n-propyl (meta) acrylate, i-propyl (meta) acrylate, n-butyl (Meta) acrylate, i-butyl (meta) acrylate, t-butyl (meta) acrylate, 2-ethylhexyl (meta) acrylate, n-octyl (meta) acrylate, i-octyl (meta) acrylate, n-nonyl (meta) acrylate, i-nonyl (meta) acrylate (Meta) equipment such as L-ester monomers: 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 2-hydroxyethyl ethyl ether, 2-hydroxyethyl (meta) Hydroxyl-containing monomers such as acrylate; carboxyl-containing monomers such as acrylic acid and methyl acrylate; Ν, Ν-dimethylaminoethyl (meta) acrylate; Amino group-containing monomers, such as Ν, Ν-Jetylaminoethyl (meta) acrylate, Ν, Ν-Jetylaminoethyl vinyl ether; glycidyl vinyl ether, glycidyl (meta) Epoxy group-containing monomers such as acrylates; trimethoxyvinylsilane, triethoxyvinylsilane, 2-trimethoxysilylethyl vinyl ether, a- Hydrolyzable silyl group-containing monomers such as tacyloxyprovir trimethoxane or the like; Siloxy group-containing monomers such as 2-trimethylsiloxyshenyl vinyl ether and 4-trimethylsiloxybutyl vinyl ether A simple substance containing a siloxycarbonyl group such as trimethylsilyl (meth) acrylate, vinyl-5-trimethylsiloquine carbonyl ester Body; and the like.

These copolymerizable monomers have a surface tension of 40 dyne / cm or less, preferably 35 dyne / cm or less, more preferably 31 dyne Z or less, of the film produced from the fluorocopolymer formed. It can be used at a rate such that it is less than cm. Here, the surface tension of the film is a value measured as follows:

In the case of a film with a surface tension of 31 dyne / cm or more, use a wetting index standard solution for multiple wetting tests with different surface tensions [manufactured by Wako Pure Chemical Industries, Ltd.] at-23 ° C and 65% RH. Apply the film linearly to the film surface under the following atmosphere. After about 3 seconds, visually determine the presence or absence of repelling, and determine the surface tension of the film surface by the number of the standard solution without repelling. In the case of a film with a surface tension of less than 31 dyne / cm, use a methanol / water mixed solution and measure the contact angle by the droplet method to determine the surface tension.

Examples of the fluororesin that can be suitably used in the present invention include, for example, polytetrafluoroethylene, tetrafluoroethylene Z perfluoroalkyl vinyl ether copolymer, and tetrafluoroethylenenohexafluro Fluoropropylene copolymer, tetrafluoroethylene z hexane Fluoropropylene z perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / ethylene copolymer, polyfluoroethylene trifluorene, ethylene trifluorene Examples thereof include a polyethylene Z-ethylene copolymer, polyvinylidene vinylidene, and polyvinyl fluoride.

Also, a mixture of these fluorine (co) polymers and other resins can be used. Other resins that can be mixed include, for example, polyester resin, polycarbonate resin, polyamide resin, and polystyrene. Resin, acrylic resin, vinyl acetate resin, polyurethane resin, phenolic resin, polyimide resin and the like.

The mixing ratio of these other resins can be such that the surface tension of the film produced from the formed resin mixture falls within the above-mentioned range.

The fluororesin which can be particularly preferably used in the present invention has a tetrafluoroethylene unit content of 15 to 85% by weight, preferably 25 to 75% by weight, more preferably 35 to 75% by weight. Examples include tetrafluoroethylene ethylene copolymer and polyvinylidene fluoride in the range of about 65% by weight. These (co) polymers generally have a weight average molecular weight in the range of 5,000 to 400,000, especially 7,000 to 300,000, from the viewpoint of processability, film durability and the like. It is desirable.

It is also possible to use a mixture of the above (co) polymer and the other resin. In this case, it is preferred that the fluorinated (co) polymer accounts for at least 70% by weight, especially 80% by weight or more, more particularly 90% by weight, based on the weight of the mixture.

Examples of commercially available (co) polymers containing a fluorinated olefin unit that can be used in the present invention include, for example, “Fluon”, “Aflon TFE”, and “Afrun COP” [all manufactured by Asahi Glass Co., Ltd.] , "Polyflon TF E", "Neoflon FEP", "Neoflon PFA", "Neoflon ETF EJ (all manufactured by Daikin Industries, Ltd.)", "Teflon TF EJ," Teflon FEP "," Teflon PFA "," Teflon EPE "and" Tefzel "[hereinafter, manufactured by DuPont-Mitsui Fluorochemicals Co., Ltd.]. The fluororesin used in the present invention includes a heat stabilizer, a light stabilizer, a cross-linking agent, as necessary, in a range that does not substantially affect physical properties such as the total light transmittance of the film and surface tension. It may contain a coloring agent and the like.

The fluororesins described above can be used, for example, by a melt extrusion method or a calendar method.

It is desirable to process the film by a hot melt molding method such as 5.

According to the present invention, the fluororesin film thus obtained is applied to an adhesive layer, preferably a pressure-sensitive adhesive layer, to form a smooth surface layer on the light incident side of the retroreflective sheet. Laminated and coated on top. In this lamination, the adhesive may be applied in advance to the surface to which the fluororesin film is adhered, or may be applied on the surface layer of the retroreflective sheet, or may be applied on an appropriate release material. An adhesive may be applied, and the adhesive may be transferred onto the sticking surface of the fluororesin film or the surface layer of the retroreflective sheet.

The thickness of the adhesive layer formed in this way is a force that can be changed according to the type of the adhesive, the thickness of the resin film to be adhered, etc., generally, 5 is to 80 // m Preferably, it can be in the range of 10 to 0 m, more preferably 20 to 60 m.

The above adhesives generally have a glass transition temperature (T g) of -100 ° C.

A pressure-sensitive adhesive mainly comprising a tacky resin having a temperature in the range of from 10 to 50 ° C, particularly from 180 to 120 ° C is suitable.

20 As the pressure-sensitive adhesive resin, those conventionally used in pressure-sensitive adhesives can be similarly used, and there is no particular limitation on the type thereof. Examples thereof include an acrylic resin, a urethane resin, and ethylene-vinyl acetate. Synthetic resins such as copolymers and silicones can be used, and among them, acrylic resins are preferred. Such acrylate resins include, for example, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, and n-hexyl acrylate. rate, Kishiruaku Li rate to 2 Echiru, n- Okuchi Ruaku Li rate, I Soo Chi Rua chestnut rate Bok, n- Noniruakuri rate Bok, C ₂ -C of Akuriru acids such Isononiruakuri rate, less _two alkyl esters One (monomer A) and acrylic acid, methacrylic acid, acrylamide, N-methylol acrylamide, 2-hydroxyshethyl acrylate, 2-hydroxyshethyl methacrylate Tg falls within the above range with at least one of the functional group-containing acrylic monomers (monomer B) Those obtained by copolymerization at such a ratio can be mentioned. The copolymerization ratio of the monomer A and the monomer B is preferably in the range of 99.5Ζ0.5 to 70Ζ30, particularly 991 to 75/25 by weight ratio of monomer A to monomer B.

Acrylic resins that are particularly preferred as the adhesive resin include butyl acrylate (Β Α) and acrylic acid (AΑ) with a weight ratio of BAZA A of 99.1 0.9 to 70730, particularly 99.5 ノ. Copolymers obtained by copolymerization in the range of 0.5 to 8020 can be mentioned.

In addition, it is preferable that the adhesive resin contains an ultraviolet absorber for the purpose of improving the weather resistance of the adhesive resin itself and the weather resistance of a retroreflective sheet serving as a base, and the like. A photooxidant can be added.

UV absorbers that can be applied to the above adhesive resins are generally The wavelength is preferably in the range of 340 to 353 nm, particularly 343 to 346 nm.Examples include ultraviolet absorbers such as cyanoacrylates, benzotriazoles, benzophenones, salicylic acids, and hydroquinones. No. Of these, the reactive type may be introduced into the polymer by reacting it with the formed polymer or by preliminarily reacting with the monomer as described above.

Specific examples of the ultraviolet absorber that can be used include benzotriazole-based ultraviolet absorbers such as 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- [ 2-Hydroxy-3,5-bis (α, -dimethylbenzyl) funyl] -2 2-benzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenylbenzotriazole Benzophenon-based UV absorbers, for example, 2-hydroxy-4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy- 2'-carboquinbenzophenone, etc .; as salicylic acid-based ultraviolet absorbers, for example, phenylsalicylate, p-octylphenyl salicylate, resorcinol monobenzoate, 4-tert-butylphenyl salicylate And so on As Noakuri rate based ultraviolet absorbers include Echiru 2- Shiano 3,3 Jifue two Ruakuri rate, 2 - Echiru hexyl-2-Shiano -3 can Rukoto cited 3- Jifuweniruakuri rates.

Of these, benzotriazole-based ultraviolet absorbers are particularly preferred. The ultraviolet absorber is usually used in an amount of 0.5 to 10 parts by weight, preferably 0.6 to 9 parts by weight, and more preferably 0.7 to 8 parts by weight, per 100 parts by weight (as solid content) of the adhesive resin. can do. Further, it is desirable that the pressure-sensitive adhesive layer contains a photooxidant in addition to the above-mentioned ultraviolet absorber. Examples of the photooxidant that can be added include a hindered amine-based or hindered phenol-based photo-oxidant. Antioxidants can be mentioned, and among them, hindered amine photooxidants are preferred. The above-mentioned hindered amide-based photooxidation inhibitor is not particularly limited, but in general, those having a high molecular weight and having an N-substituted piberdinol nucleus can be mentioned as preferable examples. . The hindered amine photooxidant preferably has a weight average molecular weight in the range of usually 400 to 10,000, particularly 500 to 5,000. Specific examples of such a hindered amine photooxidant include a high molecular ester which is an ester of butanetetracarboxylic acid and an N-substituted peridinol. As a commercially available product, MARK LA-63 (trade name ♦ A) Deca-A-Gas Co., Ltd.), MARK LA-62 (trade name: 'Ade-Riki', Argas Co., Ltd.), TI NU VIN-622 LD (trade name, manufactured by Nippon Ciba Geigy Co., Ltd.) Preferred examples can be given. By using such a high-molecular-weight hindered amide-based photooxidant, bleed-out can be prevented, and as a result, performance can be maintained for a long period of time.

The amount of the photooxidant is not strictly limited, and can be changed according to the type and the like. Generally, 100 parts by weight of the adhesive resin is used.

It can be in the range of 0.5 to 5 parts by weight (as solid content), preferably 0.6 to 4 parts by weight, more preferably 0.7 to 3 parts by weight.

The adhesive composition for forming an adhesive layer containing the above-mentioned tacky resin as a main component usually contains, in addition to the above-mentioned ultraviolet absorber and photooxidant, Components used, for example, solvents such as ethyl acetate and ethyl acetate acetate; coloring agents such as various pigments and dyes; crosslinking agents, crosslinking accelerators, and the like can be appropriately blended. Examples of the crosslinking agent include isocyanates, epoxyls, melamines, and aluminum chelates. Examples of the crosslinking accelerator include dibutyltin laurate. it can.

The adhesive composition described above can be applied to the bonding surface of the fluororesin film or to the light incident side surface of the retroreflective sheet, but practically, the fluororesin film is bonded. Apply it to the surface in advance, cover the adhesive layer with release paper, etc., and peel off the release paper when necessary, and laminate it under pressure on the incident side surface of the retroreflective sheet. Is preferred.

The surface of the retroreflective sheet of the present invention described above is protected by a fluororesin film having low surface tension and excellent weather resistance, solvent resistance, mechanical strength, etc. Even when used on the ground, there is little icing or snow accretion on the surface of the retroreflective sheeting, and no organic solvent is used when the surface of the retroreflective sheet is contaminated with paint, ink, etc. Pollution can be easily removed only by wiping or washing with water. Therefore, signs such as road signs, construction signs, etc .; Pickup plates for vehicles such as automobiles and motorcycles: Safety of clothes, life-saving equipment, etc. It can be advantageously used in sports goods such as snow poles, etc .; marking materials such as signboards.

Example

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The frost resistance test of the retroreflective sheets in Examples and Comparative Examples The methods of snow accretion test, retroreflection performance test, flexibility test and decontamination test are as follows.

(1) Ice resistance test

A retroreflective sheet is attached to the entire surface of a 7.5 x 15 cm aluminum plate to form a test piece. Stand this test piece vertically in an atmosphere of _30 ° C, spray water droplets on the entire surface of the retroreflective sheet by spraying, observe the icing condition of the surface after 24 hours, and observe the following criteria. evaluate.

5 Freezing area is less than 5% of the total area.

4 Freezing area is 5% or more and less than 10% of the total area.

3 Freezing area is 10% or more and less than 20% of the total area.

2 Freezing area is 20% or more and less than 30% of the total area.

1 Freezing area is 30% or more of the total area.

(2) Snow resistance test

A retroreflective sheet is attached to the entire surface of a 1 x 1.5 m aluminum plate to make a test piece. The test piece is placed vertically outdoors during snowfall, and the state of snow accretion on the surface 24 hours later is observed, and evaluated according to the following criteria.

5 · • · Snow covered area is less than 5% of total area.

4 · • Snow covered area is 5% or more and less than 10% of the total area.

3 · • · Snow covered area is 10% or more and less than 20% of the total area.

2 · • · Snow covered area is more than 20% and less than 30% of the total area.

1-• The snow covered area is more than 30% of the total area.

(3) Retroreflective performance

Measure in accordance with the measurement method for retroreflective performance specified in JIS Z-9-1117. The angle conditions for the measurement were: observation angle 0.2 °, incident angle 5 ° And

(4) Flexibility test

The retroreflective sheet is cut into lOxlOcm, and the pressure-sensitive adhesive provided on the back of the retroreflective sheet is placed on a vinyl chloride resin pipe of approximately 5 cπι0 at 5 ° C. Fix for 10 seconds. Then, remove the fixation and observe the adhered state, and evaluate according to the following criteria.

3 · · 'There is no sticking abnormality such as lifting or peeling.

2 · · · Affixing abnormalities such as floating and peeling are within 1 Omm from the end. 1 · · 'Affixation abnormalities such as floating or peeling exceed 10 mm from the end

(5) Pollution removal test

The surface of the retroreflective sheet is stained with oily black pen, and after drying for 5 minutes, the decontamination property is evaluated according to the following criteria.

5 · · · Can be easily wiped off with a cloth, leaving no trace.

4 · · · Wipe off with strong rubbing with cloth, leaving no trace.

3 · · · Can not be completely wiped off even if rubbed strongly with cloth. ^ Can be removed by wiping with water or ethyl alcohol on the cloth, leaving no trace at all.

2 · · · Can be removed by wiping with water or ethyl alcohol on a cloth, but leaves traces.

1 · · 'Water or ethyl alcohol cannot be removed by wiping with a cloth. Example 1

Tetrafluoroethylene ethylene copolymer fluororesin film with a thickness of about 40 // m, total light transmittance of 92%, and surface tension of 23 dyne / cm [ Fluorocarbon (COP), manufactured by Asahi Glass Co., Ltd.], and a solution of butyl acetate (BA) / acrylic acid (AA) copolymer (weight ratio: BAZAA = 90Z10) in ethyl acetate acetate toluene (4-6) (Solid content = 34%) 294 parts by weight and a benzotriazole-based ultraviolet absorber ["Tinuvin 328", manufactured by Ciba Geigy Co., Ltd.] 1.4 parts by weight, a hindered amine photooxidant ["Tinuvin 622 LD" 0.7 parts by weight, and a 1-methoxypropyl acetate-2-xylene (1Z1) solution of a hexamethylene diisocyanate-based crosslinking agent as a crosslinking agent (solid content = 75%). (%) 0.3 parts by weight of the mixed solution was coated on release paper and laminated with a dried pressure-sensitive adhesive layer having a thickness of about 50 m to produce a fluororesin film with a pressure-sensitive adhesive.

Next, the release paper is peeled off from the fluorine film with the pressure-sensitive adhesive, and it is attached and laminated on the light incident side surface of a commercially available force lens type retroreflective sheet [“Nitsuka Light ULS512”, manufactured by Nitsuka Polymer Co., Ltd.]. Thus, a retroreflective sheet having a fluororesin film-coated surface layer was obtained.

Various tests were performed on the obtained retroreflective sheets according to the above-mentioned test methods. The test results are shown in Table 1 below.

Example 2

In Example 1, in place of the tetrafluoroethylene-ethylene copolymer film, a fluorinated vinylidene resin film (PVd having a thickness of about 50 / m, a total light transmittance of 92%, and a surface tension of 25 dyne / cm) was used. F)

A retroreflective sheet was obtained in the same manner as in Example 1 except that [DX film 14S 0050, manufactured by Denki Kagaku Kogyo KK] was used. Various tests were performed on the obtained retroreflective sheet according to the above-mentioned test methods. The test results are shown in Table 1 below. Comparative Example 1

Various tests were carried out on the commercially available capsule lens type retroreflective sheet used in Example 1 in accordance with the test method. The test results are shown in Table 1 below.

Comparative Example 2

In Example 1, in place of the tetrafluoroethylene-ethylene copolymer film, a polyethylene terephthalate resin having a thickness of about 38 m, a total light transmittance of 93%, and a surface tension of 41 dyne Z cm was used. A retroreflective sheet was obtained in the same manner as in Example 1 except that a film (PET) [“Tijintetron S-38”, manufactured by Teijin Limited) was used. Various tests were performed on the obtained retroreflective sheets according to the above-mentioned test methods. The test results are shown in Table 1 below. Example 3

In Example 1, instead of using an encapsulated lens type retroreflective sheet as the retroreflective sheet, a commercially available encapsulated lens type retroreflective sheet [“Nitsuka Light SEG1502”, Nitsuka Polymer Co., Ltd. A retroreflective sheet was obtained in the same manner as in Example 1 except that the product was used. Various tests were performed on the obtained retroreflective sheets according to the above-mentioned test methods. The test results are shown in Table 1 below.

Comparative Example 3

Various tests were conducted on the commercially available encapsulated lens type retroreflective sheet used in Example 3 in accordance with the test methods described above. The test results are shown in Table 1 below.

Claims

The scope of the claims

1. A fluororesin film having a total light transmittance of 80% or more is laminated via an adhesive layer on the retroreflective sheet having a smooth surface layer on the light incident side. Retroreflective sheeting.

52. The retroreflective sheet according to claim 1, wherein the fluororesin film has a total light transmittance of 85% or more.

3. The retroreflective sheet according to claim 1, wherein the fluororesin film is a tetrafluoroethylene / ethylene copolymer or polyvinylidene fluoride.

_{1 0Ten}

4. The tetrafluoroethylene Z ethylene copolymer having a tetrafluoroethylene unit content of 15 to 85% by weight.

The retroreflective sheet according to item 3.

5. The retroreflective sheet according to claim 1, wherein the fluororesin film is produced by a melt molding method.

2. The retroreflective sheet according to claim 1, wherein the fluorine resin film has a thickness of 1 to 100 μm.

7. The retroreflective sheet according to claim 6, wherein the fluororesin film has a thickness of 5 to 80 m.

8. The method of claim 1, wherein the adhesive layer comprises a pressure-sensitive adhesive.

2 0 Shooting sheet.

9. The retroreflective sheet according to claim 8, wherein the pressure-sensitive adhesive mainly comprises an acryl-based resin.

10. The retroreflective sheet according to claim 1, wherein the adhesive layer contains an ultraviolet absorber.

1 1. The retroreflective sheet according to claim 10, wherein the ultraviolet absorber is a benzotriazole-based ultraviolet absorber.

1 2. The retroreflective sheet according to claim 10, wherein the adhesive layer further contains a photooxidant.

s 13. The retroreflective sheet according to claim 12, wherein the photooxidant is a high-molecular-weight hindered amine photooxidant.

14. The retroreflective sheet according to claim 1, wherein the adhesive layer has a thickness of 5 to 80 m.

15. The retroreflective sheet according to claim 14, wherein the adhesive layer has a thickness of 10 to 70 / m.

Five

D